Composition Dependence of the Band Gap Energy of In_xGa_1−xN Layers on GaN (x≤0.15) Grown by Metal-Organic Chemical Vapor Deposition

Abstract

We report on the composition dependence of the band gap energy of strained hexagonal In x Ga 1-x N layers on GaN with x≤0.15, grown by metal-organic chemical vapor deposition on sapphire substrates. The composition of the (InGa)N was determined by secondary ion mass spectroscopy. High-resolution X-ray diffraction measurements confirmed that the (InGa)N layers with typical thicknesses of 30 nm are pseudomorphically strained to the in-plane lattice parameter of the underlying GaN. Room-temperature photoreflection spectroscopy and spectroscopic ellipsometry were used to determine the (InGa)N band gap energy. The composition dependence of the band gap energy of the strained (InGa)N layers was found to be given by E G (x)=3.43-3.28⋅x (eV) for x≤0.15. When correcting for the strain induced shift of the fundamental energy gap, a bowing parameter of 3.2 eV was obtained for the composition dependence of the gap energy of unstrained (InGa)N.

High Al-Content AlInGaN Devices for Next Generation Electronic and Optoelectronic Applications

“…However, we do find an interesting, nonlinear band-gap dependence on strain, both for InGaN and for several bulk III-V compounds. Ordering along the [0001] direction is found to reduce the band gaps of strained wurtzite alloys considerably, producing good agreement with the measurements of Wagner et al [22] and O'Donnell et al [41]. However, discrepancies with the measurements of Wetzel et al [20] and McCluskey et al [21] remain substantial.…”

“…11. The results for random alloys fall above the measurements and are in poor agreement with them except for the results of Wagner et al [22]. Our strained wurtzite results are compared with corresponding measurements in Fig.…”

“…Recent experimental studies provided valuable insights into the properties of this alloy system [20][21][22], and two noteworthy observations have emerged from these studies: 1) Layers up to 2500 Å thick can be grown coherently on GaN in spite of the sizeable lattice mismatch (2.7% at x = 0.25, for example), and 2) The photoluminescence (PL) peak is often observed at a lower energy than the absorption edge, typically used to define the alloy band gap. Cubic (zinc-blende) In x Ga 1-x N films have also been grown recently and their properties are somewhat different from those of wurtzite In x Ga 1-x N (see below) [23,24].…”

Structural and optical properties of an InxGa1−xN/GaN nanostructure

“…The performance of the devices primarily depend on the magnitude of lattice mismatch at heterojunctions, dislocation density, interface roughness (sharpness) and in turn, localized states in the InGaN quantum wells which critically affect optical and especially, electronic properties of the devices. In order to investigate the material quality in terms of structural and optical properties under several growth procedures of the III-nitrides compounds, characterization techniques such as X-ray reflectivity (XRR), high-resolution X-ray diffractions (HXRD), atomic force microscopy (AFM), photoluminescence (PL) and spectroscopic ellipsometry (SE) are widely used [3][4][5][6][7][8]. To improve the performance of nitridebased optoelectronic and microelectronic devices, various growth procedures have been employed which indicates that a better knowledge of their growth kinetics, surface dynamics and lattice structures is necessary.…”

Compositional dependence of the strain-free optical band gap in InxGa1−xN layers

“…A deviation from a linear dependence of the fundamental gap has been postulated, with a wide range of bowing parameters, in the literature. [6][7][8][9][10][11][12][13][14] Several sources of error hamper the establishment of a consensual relation. In some studies the measured quantity is the luminescence peak energy, with ignores the Stokes' shifted 15,16 of emission with respect to the band edge.…”